Field
Methods for delivering treatment agents to coronary vessels. In particular, methods and kits for delivering treatment agents to tissues or spaces adjacent to coronary vessels.
Background
Cardiovascular diseases of the heart or blood vessels continue to affect individuals within the United States and many Western countries at increasingly alarming rates. A major component of morbidity and mortality attributable to cardiovascular disease occurs as a consequence of the partial or complete blockage of vessels carrying blood in the coronary and/or peripheral vasculature caused by diseased vessels. When such vessels are partially occluded, lack of blood flow causes ischemia of the muscle tissues supplied by such vessel, consequently inhibiting muscle contraction and proper function. Total occlusion of blood flow causes necrosis of the vasculature and muscle tissues.
Myocardial infarction (MI) is one form of heart disease that often results from the sudden lack of supply of oxygen and other nutrients. The lack of blood supply is a result of closure of the coronary artery that nourishes a particular part of the heart muscle. The cause of this event is generally attributed to arteriosclerosis, “hardening of the arteries”, in coronary vessels.
Formerly, it was believed that an MI was caused from a slow procession of closure from, for example, 95 percent then to 100 percent but an MI can also be a result of minor blockages where, for example, there is rupture of the cholesterol plaque resulting in blood clotting within the artery. Thus, the flow of blood is blocked and downstream cellular damage occurs. This damage can cause irregular rhythms that can be fatal, even though the remaining muscle is strong enough to pump a sufficient amount of blood. As a result of this insult to the heart tissue, scar tissue tends to naturally form.
Blood vessel stenosis or occlusions are commonly treated by mechanically enhancing blood flow in the affected vessels. Such mechanical enhancements often employ surgical techniques that attach natural or synthetic conduits around the occlusion, thereby providing bypass grafts, or employ revascularization by various means to physically enlarge the vascular lumen at the site of occlusion. These revascularization procedures involve balloons, endovascular knives (atherectomy), and endovascular drills. Significant morbidity and even mortality frequently accompany surgical approaches, while, in many cases, recurrent stenoses complicate angioplasty-type processes.
Systemic, local or direct drug delivery techniques designed to treat damaged heart and vasculature tissues may accompany or replace mechanical techniques. Such techniques, however, can be problematic for a number of reasons. In particular, in systemic delivery techniques, the whole organism is treated therefore greater amounts of drugs must be supplied which are sometimes toxic to the organism. In local delivery techniques the therapeutic is typically injected into a blood stream at a point upstream from the treatment site or into an unperfused vessel region after first occluding the vessel region to inhibit blood flow. In either case, once blood flow is restored, as it must be to prevent further damage to the vessel, the therapeutic is washed away from the region where delivery is desired. Lastly, in direct delivery, typically, the drug is delivered through a vessel wall into dense tissues having few spaces for accommodating fluid uptake. Accordingly, administering an effective drug amount may require several injections to the region.